1. Field of the Invention
The invention relates to a nailing depth adjustable device for a nail gun, more particularly to a nailing depth adjustable device including a telescopic adjusting unit for adjusting a traveling distance of a barrel-extending part.
2. Description of the Related Art
Referring to FIG. 1, Taiwanese Patent Number 210509 discloses a conventional pneumatic nail gun 1 including: a gun housing 11 having a front end; a barrel 12 extending frontwardly from the front end of the gun housing 11 in a nail-discharging direction; a magazine 13 connected to a rear end of the barrel 12 for supplying nails into the rear end of the barrel 12; an actuating mechanism mounted in a lower part of the gun housing 11 and including an actuating member (not shown) movable between enable and disable states for enabling and disabling discharging of the nails through the barrel 12, and a trigger 14 for triggering discharging of the nails when the actuating member is disposed at the enabling state; a barrel-extending part 15 mounted slidably on the barrel 12 so as to be slidable on the barrel 12 in the nail-discharging direction and having a front open end 151 adapted for abutting against an object (not shown) to be nailed and for serving as a nail-discharging outlet; a driving part 16 supported movably on the gun housing 11, extending toward the actuating member, and having a driving end 161 for driving movement of the actuating member and a supporting end opposite to the driving end 161; and a telescopic adjusting unit disposed at an upper side of the barrel 12 and including an operating screw nut 17 mounted rotatably on the supporting end of the driving part 16, and a screw rod 18 secured to the barrel-extending part 15 and engaging threadedly the operating screw nut 17.
Rotation of the operating screw nut 17 relative to the screw rod 18 results in movement of the barrel-extending part 15 in the nail-discharging direction, thereby permitting adjustment of the distance (L) between the front open end 151 of the barrel-extending part 15 and the driving end 161 of the driving part 16 in the nail-discharging direction.
In use, the front open end 151 of the barrel-extending part 15 is pressed against the object to be nailed such that the barrel-extending part 15, the telescopic adjusting unit and the driving part 16 are co-moved rearwardly relative to the gun housing 11 in the nail-discharging direction by a fixed distance so as to drive the actuating member from the disabling state to the enabling state. The trigger 14 is subsequently pushed to trigger discharging of the nails. Since the moving distance of the barrel-extending part 15 relative to the gun housing 11 is fixed during a nailing operation, the longer the distance (L) between the front open end 151 of the barrel-extending part 15 and the driving end 161 of the driving part 16, the shallower will be the depth for the nail to penetrate into the object.
Referring to FIG. 2, Taiwanese patent publication number 441470 discloses another conventional pneumatic nail gun 6 including: a gun housing 61; a barrel 62 extending from the gun housing 61; a barrel-extending part 63 mounted slidably on the barrel 62; a driving part 64 for moving an actuating member (not shown) to move from a disabling state to an enabling state; and a telescopic adjusting unit 65 coupled to the barrel-extending part 63 and the driving part 64. The conventional pneumatic nail gun 6 has a structure differing from that of the aforesaid conventional pneumatic nail gun 1 mainly in that the telescopic adjusting unit 65 is disposed at a lower side of the gun housing 61.
Each of the aforesaid conventional pneumatic nail guns 1, 6 requires movement of the respective barrel-extending part 15, 63 relative to the barrel 12, 62 in the nail-discharging direction to a desired position so as to adjust the distance (L) between the front open end 151 of the barrel-extending part 15, 63 and the driving end 161 of the driving part 16, 64 and therefore to adjust the desired nailing depth.